DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[4910-13-P] 

[Docket No. FAA-2009-0776; Directorate Identifier 2009-NE-32-AD; Amendment 

39-17481; AD 2010-17-11R1] 

RIN 2120-AA64 

Airworthiness Directives; Dowty Propellers Propellers 

AGENCY: Federal Aviation Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are revising an existing airworthiness directive (AD) that applies to all 

Dowty Propellers R408/6-123-F 117 model propellers. That AD currently requires initial 

applications of sealant between the bus bar assembly and the backplate assembly of 

certain line-replaceable units, and repetitive applications of sealant on all R408/6-123-

F 117 model propellers. This new AD requires the same actions and allows the use of an 

equivalent sealant as prescribed in revised service information. This AD was prompted 

by the need to add an optional terminating action to the applications of sealant. We are 

issuing this AD to prevent an in-flight double generator failure, which could result in 

reduced control of the airplane. 

DATES: This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

The Director of the Federal Register approved the incorporation by reference of a 

certain publication listed in the AD as of [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

ADDRESSES: 

For service information identified in this AD, contact Dowty Propellers, Anson 
Business Park, Cheltenham Road East, Gloucester GL2 9QN, UK; phone: 44 (0) 1452 

716000; fax : 44 (0) 1452 716001. You may view this service information at the FAA, 

Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA. For 

information on the availability of this material at the FAA, call 781-23 8-7125. 

Examining the AD Docket 

You may examine the AD docket on the Internet at http://www.regulations.gov; 

or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. The AD docket contains this AD, the regulatory 

evaluation, any comments received, and other information. The address for the Docket 

Office (phone: 800 647 5527) is Document Management Facility, U.S. Department of 

Transportation, Docket Operations, M 30, West Building Ground Floor, Room W12 140, 

1200 New Jersey Avenue SE., Washington, DC 20590. 

FOR FURTHER INFORMATION CONTACT: Michael Schwetz, Aerospace 

Engineer, Boston Aircraft Certification Office, FAA, Engine and Propeller Directorate, 

12 New England Executive Park, Burlington, MA 01803 ; phone: 781-238-7761; fax 

781-23 8-7170; email: michael.schwetz@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to 

revise AD 2010-17-11 , Amendment 39-16403 (75 FR 51656, August 23, 2010). That AD 

applies to the specified products. The NPRM published in the Federal Register on 

February 7, 2013 (78 FR 9005). That NPRM proposed to add an optional terminating 

action to the applications of sealant. 

2 
Comments 

We gave the public the opportunity to participate in developing this AD. The 

following presents the comments received on the proposal and the FAA's response to 

each comment. 

Request to Add Revised Service Information 

Horizon Air requested that we reference the latest revision of Dowty Alert Service 

Bulletin (ASB) No. D8400-61-A66, which is Revision 7, dated December 1, 2011 in the 

Compliance and the Credit for Previous Actions sections of the final rule. 

We partially agree. We changed paragraph (e)(l)(ii) ofthe Compliance section to 

read, "Use paragraph 3 of the Accomplishment Instructions of Dowty Propellers Alert 

Service Bulletin (ASB) No. D8400-61-A66, Revision 7, dated December 1, 2011 to apply 

the sealant." We do not agree with the change to the Credit for Previous Actions 

paragraph because referencing the ASB in the Compliance paragraph satisfies this 

request by directing the use of the latest revision as stated. 

Request to Add Equivalent Sealant 

Horizon Air requested that we allow the use of 3M 4200 sealant as an equivalent 

replacement for the 3M 5300 sealant listed in the Accomplishment Instructions of Dowty 

Propellers Service Bulletin (SB) No. D8400-61-94, Revision 3, dated October 23, 2012. 

We agree. We changed the AD by modifying references to "sealant" to "3M 5300 

or 3M 4200 sealant" in the Compliance and Installation Prohibition paragraphs. 

Conclusion 

We reviewed the relevant data, considered the comments received, and 

determined that air safety and the public interest require adopting the AD with the 

changes described previously and minor editorial changes. We have determined that these 

minor changes: 

3 
• Are consistent with the intent that was proposed in the NPRM (78 FR 9005, 

February 7, 2013 ) for correcting the unsafe condition; and 

• Do not add any additional burden upon the public than was already proposed 

in the NPRM (78 FR 9005, February 7, 2013). 

Differences Between This AD and the Service Information 

Dowty Propellers SB No. D8400-61-94, Revision 3, dated October 23, 2012 

requires the application of 3M 5300 sealant between the bus bar assembly and the 

backplate assembly of Dowty Propeller R408/6-123-F/17. This AD also permits use of 

3M 4200 sealant as an acceptable equivalent to the 3M 5300 sealant. 

Costs of Compliance 

We estimate that this AD will affect about 104 propellers installed on airplanes of 

U.S. registry. We also estimate that it will take about 3 hours per propeller to apply the 

sealant and that required sealant will cost about $20 per propeller. We also estimate that it 

will take about 3 hours to replace the bus bar with a de-icer slip ring harness and that 

required parts will cost about $1,200 per propeller. The average labor rate is $85 per 

hour. Based on these figures, we estimate the cost of the AD on U.S. operators to be 

$171,080. 

Authority for this Rulemaking 

Title 49 of the United States Code specifies the FAA's authority to issue rules on 

aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. 

Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's 

authority. 

We are issuing this rulemaking under the authority described in Subtitle VII, 

Part A, Subpart III, Section 44701 , "General requirements." Under that section, Congress 

charges the FAA with promoting safe flight of civil aircraft in air commerce by 

prescribing regulations for practices, methods, and procedures the Administrator finds 

4 
necessary for safety in air commerce. This regulation is within the scope of that authority 

because it addresses an unsafe condition that is likely to exist or develop on products 

identified in this rulemaking action. 

Regulatory Findings 

We have determined that this AD will not have federalism implications under 

Executive Order 13132. This AD will not have a substantial direct effect on the States, on 

the relationship between the national government and the States, or on the distribution of 

power and responsibilities among the various levels of government. 

For the reasons discussed above, I certify that this AD: 

(1) Is not a "significant regulatory action" under Executive Order 12866, 

(2) Is not a "significant rule" under DOT Regulatory Policies and Procedures 

( 44 FR 11034, February 26, 1979), 

(3) Will not affect intrastate aviation in Alaska to the extent that it justifies 

making a regulatory distinction, and 

( 4) Will not have a significant economic impact, positive or negative, on a 

substantial number of small entities under the criteria of the Regulatory Flexibility Act. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. 

Adoption of the Amendment 

Accordingly, under the authority delegated to me by the Administrator, the FAA 

amends 14 CFR part 39 as follows: 

PART 39 -AIRWORTHINESS DIRECTIVES 

1. The authority citation for part 39 continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

5 
§ 39.13 [Amended] 

2. The FAA amends§ 39.13 by removing airworthiness directive (AD) 

2010-17-11, Amendment 39-16403 (75 FR 51656, August 23, 2010), and adding the 

following new AD: 

2010-17-11R1 Dowty Propellers: Amendment 39-17481; Docket No. FAA-2009-0776; 

Directorate Identifier 2009-NE-32-AD. 

(a) Effective Date 

This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

(b) Affected ADs 

This AD revises AD 2010-17-11, Amendment 39-16403 (75 FR 51656, August 

23, 2010). 

(c) Applicability 

This AD applies to Dowty Propellers R408/6-123-F/17 model propellers. 

(d) Unsafe Condition 

This AD was prompted by the need to add an optional terminating action to the 

applications of sealant. We are issuing this AD to prevent an in-flight double generator 

failure, which could result in reduced control of the airplane. 

(e) Compliance 

Comply with this AD within the compliance times specified, unless already done. 

(1) For R408/6-123-F/17 model propellers with a hub, actuator, and backplate 

assembly line-replaceable unit serial number below DAP0347, do the following initial 

sealant application within 5,000 flight hours (FHs) after September 27,2010, or within 

100 FHs from the effective date ofthis AD, whichever occurs later: 

(i) Apply 3M 5300 or 3M 4200 sealant between the bus bar assemblies and the 

backplate assembly. 

6 
(ii) Use paragraph 3 ofthe Accomplishment Instructions of Dowty Propellers 

Alert Service Bulletin (ASB) No. D8400-61-A66, Revision 7, dated December 1, 2011 , 

to apply the sealant. 

(2) Thereafter, for all R408/6-123-F/17 model propellers, re-apply sealant as 

specified in paragraphs (e)(1)(i) through (e)(1)(ii) of this AD within every additional 

10,000 FHs. 

(f) Installation Prohibition 

After the effective date of this AD, do not install any Dowty Propellers R408/6-

123-F/17 model propeller unless 3M 5300 or 3M 4200 sealant has been applied between 

the bus bar assembly and the backplate assembly as specified by this AD, or unless the 

optional terminating action as specified in paragraph (h) of this AD has been performed. 

(g) Credit for Previous Actions 

Sealant applications performed before the effective date of this AD that followed 

Dowty Propellers Service Bulletin (SB) No. D8400-61-66, dated February 9, 2007, 

Revision 1, dated May 4, 2007; ASB No. D8400-61-A66, Revision 2, dated August 19, 

2009; Revision 3, dated November 10, 2009; Revision 4, dated January 19, 2010; 

Revision 5, dated June 16, 2010, or Revision 6, dated August 17, 2011 satisfy the initial 

sealant application requirement of this AD. 

(h) Optional Terminating Action 

As optional terminating action to the sealant application requirements ofthis AD, 

replace the bus bar assembly with a slip ring de-icer harness. Use paragraph 3.A. of the 

Accomplishment Instructions of Dowty Propellers SB No. D8400-61-94, Revision 2, 

dated August 29, 2012, or Revision 3, dated October 23, 2012, to do the replacement. 

(i) Alternative Methods of Compliance (AMOCs) 

The Manager, Boston Aircraft Certification Office, FAA, may approve AMOCs 

for this AD. Use the procedures found in 14 CFR 39.19 to make your request. 

7 
U) Related Information 

(1) Refer to European Aviation Safety Agency AD 2009-0114R1 (correction: 

dated December 12, 2012) for related information. 

(2) For more information about this AD, contact Michael Schwetz, Aerospace 

Engineer, Boston Aircraft Certification Office, FAA, Engine and Propeller Directorate, 

12 New England Executive Park, Burlington, MA 01803; phone: 781-238-7761; fax 781-

238-7170; email: michael.schwetz01faa.gov. 

(k) Material Incorporated by Reference 

(1) The Director ofthe Federal Register approved the incorporation by reference 

(IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR 

part 51. 

(2) You must use this service information as applicable to do the actions required 

by this AD, unless the AD specifies otherwise. 

(3) The following service information was approved for IBR on [INSERT DATE 

35 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. 

(i) Dowty Propellers Alert Service Bulletin No. D8400-61-A66, Revision 7, dated 

December 1, 2011. 

(ii) Reserved. 

( 4) For service information identified in this AD, contact Dowty Propellers, 

Anson Business Park, Cheltenham Road East, Gloucester GL 29QN, UK; phone: 44 (0) 

1452 716000; fax: 44 (0) 1452 716001. 

(5) You may view this service information at the FAA, Engine & Propeller 

Directorate, 12 New England Executive Park, Burlington, MA. For information on the 

availability ofthis material at the FAA, call 781-238-7125. 

(6) You may view this service information at the National Archives and Records 

Administration (NARA). For information on the availability ofthis material at NARA, 

8 
call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibrlocations.html. 

Robert Ganl y, 

Acting Assistant Manager, Engine & Propeller Directorate, 

Aircraft Certification Service. 

9